Databases are computerized information storage and retrieval systems. There are many different types of databases. One particular type of database is a relational database that includes a relational database management system (RDBMS). A relational database management system (RDBMS) is a database management system (DBMS) which uses relational techniques for storing and retrieving data. Relational databases are organized into physical tables which consist of rows and columns of data. The rows are formally called “tuples”. A database will typically have many physical tables and each physical table will typically have multiple tuples and multiple columns. The physical tables are typically stored on random access storage devices (DASD) such as magnetic or optical disk drives for semi-permanent storage.
Increasingly, applications are storing XML documents, or parts thereof, in relational databases. An XML document can be stored in a relational database though a process of decomposition—i.e., breaking the XML document into component pieces (or portions) and storing the component pieces in the relational database. The specification of the component pieces and where the component pieces are to be stored in the relational database is typically accomplished through a mapping document. The mapping document contains information as to which XML elements/attributes are mapped to which table and column in the relational database.
On each decomposition operation, along with the XML document to be decomposed, the mapping document is also typically supplied by the user. The mapping document must be parsed to extract mapping information, which must then be processed and transformed into internal data structures for use during the actual decomposition of the XML document. A single mapping document can be used to decompose any instance XML document that conforms to the structure that the mapping document describes. Accordingly, the same mapping document can be used to decompose many XML documents over any time period. Conventional techniques for decomposing an XML document, however, may not save the results of the processing of the mapping document and, therefore, the same processing of the mapping document must be repeated each time a different XML document is decomposed.
Accordingly, what is needed is an improved technique of processing the mapping information which reduces the amount of time required to decompose XML documents. The present invention addresses such a need.